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Tesla sets charge limit to 90%
- Thread starter Iron
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I will give it a try on a weekday next. I also will try it later in the day as I wondered if my test at ~11AM caused it to want to charge right away as it was a long time till the set 7:45AM the next day.
I'm on Tesla WC off of a 50A breaker so set to charge at 40A. My test yesterday was 30-50%. But my normal weekday charging is only adding 4% each day. Usually I have that set at 65%, plug in around 5:30PM. I'll try that on Monday evening. My Scheduled departure and Off peak are set for all 7 days of the week though. I just sometimes mess around with the % and times on the weekends.
Can I just double check that you aren't using Scheduled Charging setting? You have that to Off? Only reason is you mentioned that weekdays vs all week is an Off-Peak setting but it is both a Scheduled Departure and an Off-Peak setting. Only Scheduled Charging doesn't have that option. Scheduled Charging and Scheduled Departure don't work together AFAIK. My Scheduled Charging (2nd tab on the app's charging settings) is turned off as all my schedule is controlled by scheduled departure and off-peak.
Yes, scheduled charging is off. Lemme ask, is it truly charging to completion as soon as you plug up? Can't quite recall but I think mine flash for a minute like it would start to charge, then shut down the charging, either that, or it went blue. On the app, it would have a message something like "ready to depart at 6:30".... I'll try to grab a screen shot on Monday.
I haven't left it to charge to check if it keeps going. With Off-Peak turned off, I plugged in, it went green, the car screen said charging and said 2hr something to compete charging. Only left it like that for 30s or so. When Off-Peak is turned on, I plug in, flashes green for 1-2s and then back to blue.
I will try letting it continue next time to see if it keeps on going when off-peak is off.
Killer Junior
Tesla FNG
Set it and forget it. Or just do what you want. I tend to err on the side of whatever the company recommends. But TETO.
my 5 cents.
I set it to 80% SOC and keep my car always plugged in. Even if I just had a quick trip to buy groceries and used just 2% of the battery, when I am back in the garage - I plug it in. That simple.
I set it to 80% SOC and keep my car always plugged in. Even if I just had a quick trip to buy groceries and used just 2% of the battery, when I am back in the garage - I plug it in. That simple.
johnny_cakes
Member
Can you tell us more about this? After the range estimation drop, did the BMS recalibrate by charging to 90% nightly? And did the range estimate return to normal?
I settled on charging to 75%. Plugging in daily and charging to depart by early morning Occasionally I charge to 90% if relatives are in town or im doing long runs.
My battery percentage never drops below 50% and I don't know if that's a bad thing because lately my scheduled charging overshoots the set percentage by a few points. If I set to 75, it charges to 77%. If set to 90, it charges to 92, etc. Anyone experiencing this? Im thinking I need to stop being anal and let it drop to about 10% now and then.
My battery percentage never drops below 50% and I don't know if that's a bad thing because lately my scheduled charging overshoots the set percentage by a few points. If I set to 75, it charges to 77%. If set to 90, it charges to 92, etc. Anyone experiencing this? Im thinking I need to stop being anal and let it drop to about 10% now and then.
OxBrew
Active Member
That's all totally normal. Don't worry about anything, everything you're doing is fine.
If you take a longer trip maybe 6 times a year, and it gets down around 10-20% SOC, and sleeps at night, your SOC estimate will stay calibrated (or something like that).
If you never do that, it still won't hurt anything. Just know your SOC prediction might be a bit off, and add a bit of buffer on the first few legs of a longer trip, just to be safe (ie, charge 5-10% more than the car thinks you need).
I charge a lot like you do, 50-55 or 45-75% most days.
On long trips every 6-8 weeks, the first 2 legs are usually a bit off on the arrival SOC, up or down by as much as 10%.
Somewhere around the 3rd or 4th leg, it starts predicting within 2-3%.
Through all of this, your battery is fine, nothing is actually changing in the actual capacity of the battery. The computer calibration just drifts a bit.
Thanks for the reassurance. I hope that one day Tesla pushes out a software update that can prevent the calibration from drifting, or provide tools that can easily get it back in alignment. I've heard of something in the service menu that can do this but also that it's difficult to use and can be dangerous to the battery if used improperly.
SageBrush
REJECT Fascism
They can last 15 years if the pack is not abused. That the car may have more than one owner is a different matter.
I do the best I can for my pack, in the context of a couple of things:
1. Lets me use clean energy
2. Convenient for my wife and me, and does not provoke range anxiety
In practice this works out to plugging in about daily, and changing *when* the car charges in the summer Vs winter. We are retired and share one car. Charging up to ~ 70% works well for us. For trips I top off in the morning before we leave.
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There are many possible points of failure in the battery pack. Corrosion, bad cells, broken welds, faulty temperature sensors, pyro fuses. These can and do sometimes fail and brick a battery pack.
SageBrush
REJECT Fascism
There are many points of failure in a human. That is no reason to get fat, smoke, or walk across streets with your eyes closed.
Since you brought up humans, I would not bet against the actuarial tables to plan on living to 100+ years. The odds are against it happening.
Although my utility TOU rate doesnt have off peak rates till June thru Sept, I decided to get used to charging at the off peak time. It completes charging about 20 min before I leave and spends most sitting time in the high or low 60s percentage before being charged again.
I must say charging at home is phenomenal. Since early Feb, it's cost me 40 bucks total to charge this thing and that's with a daily commute. That's half a week's worth of gas in my truck
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SageBrush
REJECT Fascism
That is a most excellent routine. I don't use it because our car use is too variable and I don't want the sit sitting around at high SOC, but it matches your use profile very well
As an aside to others, this is a good example of why it is best to match the charging routine to one's local weather, range demands, energy profile and usage profile. There is not a one size fits all charging routine.
In reality, it actually is very easy to measure, but that requires you to run the battery down. That's where the problem starts.
This isn't a Tesla problem, it's a physics problem. Sure, Tesla may make it a little better, It's really hard to measure the electrons.
According to this study, keeping the charge between 65%-75% is ideal. But 45% to 75% is more practical. 30% roughly 100 miles is good enough for my daily commute.
View attachment 908844
That research report that the picture comes from is flawed. There is more than one explanation here on TMC so I wont go trough that again. (Search if you lije to know).
Degradation cones from cyclic aging and calendar aging.
Calendar aging will cause the most of the degradation for most cars for the 5-8 years from new.
This is from a research report of panasonic NCA chemistry, like any US LR or P.
The lower the SOC, the lower the calendar aging. If kept below 55% displayed SOC (57%) true SOC, it cut the calendar sging in half compared to 60 or above.
One other strategy that makes a difference is “charge late” to minimize the time at high SOC (high should be considered 60-65% or more in this case. The charging could be set to be finisched sbout the same time as the drive is to commence, or with a small margin (1-2hrs, the shorter the better).
(Virtually all research supports this. Its not a one and only test, its “facts” supported by many research tests).
In general, the batteries will survive the eight years of warranty anyway, but takings good care of the battery might make a huge difference in long term degradation and about double the useful life.
So, no need to care but it will make a clear difference.
For cyclic aging, in general, the lower the SOC and the smaller cycles, the smaller the cyclic aging.
To sum this up:
-Only charge whats needed (incl. a anxiety margin) until next charge.
-Charge often. It will reduce the needed SOC in the above point.
-Charge late, if possible leave the car not charged until it need to start charging to be ready for the next drive.
For cycles, this is a test of a Panasonic 18650 NCA cells (very close to Model S/X, and not far from model 3/Y with NCA chemistry) with different charging levels.
3.7V = about 50% SOC
3.8V = about 60% SOC
3.9V = about 70% SOC
4.0V = about 80% SOC
4.1V = about 90% SOC
4.2V = 100% SOC.
Charging to 50% cut the cyclic degradation in half in this case compared to 80-90%, but all cycling is to a set level.
When using fixed DoD (depth of discharge), the difference get smaller, but its still there.
Here’s cycles with comparable DoD at different SOC, also different DoD at comparable SOC.
Again:
3.7V = about 50% SOC
3.9V = about 70% SOC
4.1V = about 90% SOC
We can se that a charging target to 50% (3.7V) with 20% DoD causes the least degradation in this case. If we look at the 25C cycles, 50% with 20% DoD degrades about 6.5% after 1000 FCE cycles.
70% (3.9V) at 20% DoD degrades about 9.5% after 1000 FCE cycles.
90% (4.1V) at 20% DoD degrades about 12% after 1000 FCE cycles.
So a 50% charging target with 20% depth of discharge basically cut the degradation (cyclic aging) in half compared to charging to 80-90% with the same DoD (same miles driven).
The chart above doesnt show what happens below 3.7V /50%.
Here’s a chart about that, but in this case it is not Panasonic NCA.
In this case it is quite obvious that these cells degrade less from cycles the lower the SOC-range is.
3.7V = about 50% SOC
3.8V = about 60% SOC
3.9V = about 70% SOC
4.0V = about 80% SOC
4.1V = about 90% SOC
4.2V = 100% SOC.
Charging to 50% cut the cyclic degradation in half in this case compared to 80-90%, but all cycling is to a set level.
When using fixed DoD (depth of discharge), the difference get smaller, but its still there.
Here’s cycles with comparable DoD at different SOC, also different DoD at comparable SOC.
Again:
3.7V = about 50% SOC
3.9V = about 70% SOC
4.1V = about 90% SOC
We can se that a charging target to 50% (3.7V) with 20% DoD causes the least degradation in this case. If we look at the 25C cycles, 50% with 20% DoD degrades about 6.5% after 1000 FCE cycles.
70% (3.9V) at 20% DoD degrades about 9.5% after 1000 FCE cycles.
90% (4.1V) at 20% DoD degrades about 12% after 1000 FCE cycles.
So a 50% charging target with 20% depth of discharge basically cut the degradation (cyclic aging) in half compared to charging to 80-90% with the same DoD (same miles driven).
The chart above doesnt show what happens below 3.7V /50%.
Here’s a chart about that, but in this case it is not Panasonic NCA.
In this case it is quite obvious that these cells degrade less from cycles the lower the SOC-range is.
@AAKEE
So, in my situation, I drive about 25 miles a day. For the best results, I plan to charge to 50-55%. Would you recommend charging everyday even though my SOC at the end of the day is around 40-45% or should I charge every 3-4 days when my SOC is down to 20%? Also, I will plan to schedule my charging to happen closer to leaving home in the AM when I do go to hook up. Thanks for the info!
Chad
So, in my situation, I drive about 25 miles a day. For the best results, I plan to charge to 50-55%. Would you recommend charging everyday even though my SOC at the end of the day is around 40-45% or should I charge every 3-4 days when my SOC is down to 20%? Also, I will plan to schedule my charging to happen closer to leaving home in the AM when I do go to hook up. Thanks for the info!
Chad
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